The present invention relates to containers of branched polycarbonate, to the production thereof and to the use thereof and to branched polycarbonate.
Containers of polycarbonate are known.
Containers of polycarbonate exhibit numerous advantageous properties, such as for example elevated transparency, good mechanical properties, elevated resistance to environmental influences and a long service life together with low weight and straightforward, low-cost producibility.
Polycarbonate containers are produced, for example, using the extrusion blow moulding process or the injection blow moulding process.
In the extrusion blow moulding process, the pellets are generally melted with a single screw extruder and are shaped by a die to form a free-standing tube, which is subsequently enclosed by a blowing mould, which pinches together the bottom of the tube. The tube is inflated within the mould, thus being shaped as desired. After a cooling period, the mould is opened and the hollow article may be removed (a more detailed description may be found, for example, in Brinkschrxc3x6der, F. J., Polycarbonate in Becker, Braun, Kunststoff-Handbuch, volume 3/1, Polycarbonate, Polyacetale, Polyester, Celluloseester, Carl Hanser Verlag, Munich, Vienna 1992, pages 257 to 264).
It is advantageous to use a highly pseudoplastic polycarbonate for extrusion blow moulding in order to ensure elevated melt stability. Branched polycarbonates are particularly pseudoplastic.
The injection blow moulding process is a combination of injection moulding and blow moulding.
The process proceeds in three stages:
1) injection moulding of the parison in the plastic temperature range of the polycarbonate
2) inflation of the parison in the thermoplastic range of the polycarbonate (the core of the injection moulding tool is simultaneously the blowing mandrel)
3) stripping of the hollow article and, optionally, cooling of the blowing mandrel with air
(a more detailed description may be found, for example, in Anders, S., Kaminski, A., Kappenstein, R., Polycarbonate in Becker, Braun, Kunststoff-Handbuch, volume 3/1, Polycarbonate, Polyacetale, Polyester, Celluloseester, Carl Hanser Verlag, Munich, Vienna 1992, pages 223 to 225).
Known containers of polycarbonate exhibit the disadvantage that they do not meet certain requirements for practical use. If known containers of polycarbonate are subjected to severe mechanical stress, the container may burst. This may occur, for example, if a liquid-filled container is dropped from some height onto the ground, for example from the loading area of a truck in which the container is being transported. Such mechanical loads may, for example, be simulated by the drop test as is described in the present text.
The object of the invention is accordingly to provide containers of polycarbonate which have greater breaking strength than known containers of polycarbonate when subjected to severe mechanical stress.
The object according to the invention is achieved by containers of branched polycarbonate, characterised in that, at 260xc2x0 C. and a shear rate of 10 sxe2x88x921, the polycarbonate has a melt viscosity of 5500 to 9000 Pas, preferably of 6000 to 8000 Pas and particularly preferably of 6500 to 8000 Pas and, at 260xc2x0 C. and a shear rate of 1000 sxe2x88x921, a melt viscosity of 880 to 1500 Pas, preferably of 900 to 1500 Pas and particularly preferably of 950 to 1200 Pas and that it has an MFR (melt flow index, measured to ISO1133) of 0.1 to 3.0 g/10 min, preferably of 0.5 to 2.8 g/10 min and particularly preferably of 0.5 to 2.5 g/10 min.
The containers of branched polycarbonate are preferably characterised in that phenol and/or alkylphenols and/or arylphenols are used in the production of the branched polycarbonate, with alkylphenols and/or arylphenols being particularly preferred and alkylphenols being very particularly preferred.
The containers of branched polycarbonate are furthermore preferably characterised in that phenol is used in the production of the branched polycarbonate and that the branched polycarbonate contains 1,1,1-tris(4-hydroxyphenyl)ethane (THPE) and/or 3,3-bis(3-methyl-4-hydroxyphenyl)-2-oxo-2,3-dihydroindole (IBK, isatin biscresol) as branching agent.
The containers of branched polycarbonate are furthermore preferably characterised in that the polycarbonate has a branching index at 260xc2x0 C., defined as the quotient of melt viscosity at a shear rate of 10xe2x88x921 and 1000 sxe2x88x921, of 6 to 12, preferably of 7 to 12 and particularly preferably of 7 to 10. The branching index is abbreviated to SV index.
The containers of branched polycarbonate are furthermore preferably characterised in that alkylphenols and/or arylphenols are preferably used in the production of the branched polycarbonate, with alkylphenols being particularly preferred and that the branched polycarbonate contains 1,1,1-tris(4-hydroxyphenyl)ethane (THPE) and/or 3,3-bis(3-methyl-4-hydroxyphenyl)-2-oxo-2,3-dihydroindole (IBK, isatin biscresol) as branching agent.
The containers of branched polycarbonate are particularly preferably characterised in that p-tert.-cumylphenol is used as the arylphenol in the production of the branched polycarbonate.
The containers of branched polycarbonate are furthermore particularly preferably characterised in that p-tert.-butylphenol or isooctylphenol is used as the alkylphenol in the production of the branched polycarbonate.
These containers are accordingly provided by the present invention.
The present invention also provides the production of the containers according to the invention.
The present invention also provides the use of the containers according to the invention.
The present invention also provides the branched polycarbonates of which the containers consist and which have the above-stated features.